The present invention relates to an internal combustion engine controller applied to an internal combustion engine including an in-cylinder injection valve that injects fuel into a cylinder. The present invention also relates to a learning method of a learning value in the internal combustion engine.
An internal combustion engine controller that causes an in-cylinder injection valve to perform partial lift injection terminating fuel injection before a valve body reaches a fully open position and a full lift injection to terminate fuel injection after the valve body reaches the fully open position is known in the art. In the controller described in Japanese Laid-Open Patent Publication No. 2015-190318, a learning process of the partial lift injection is performed when a predetermined learning condition is satisfied.
When the learning process of the partial lift injection is performed, a requested injection amount for an in-cylinder injection valve is divided into a set injection amount, which is an injection amount for full lift injection, and a predetermined injection amount, which is an injection amount for partial lift injection. Full lift injection is first performed to drive the in-cylinder injection valve based on the set injection amount. Then, partial lift injection is performed to drive the in-cylinder injection valve based on the predetermined injection amount. When the partial lift injection is performed in such a manner, the injection characteristic of the in-cylinder injection valve when caused to perform the partial lift injection is learned so that a deviation of a target value of a valve closing time of the in-cylinder injection valve specified from the predetermined injection amount and an actual valve closing time of the in-cylinder injection valve approaches “0” in the learning process.
The injection characteristic obtained by the learning process of the partial lift injection is stored in a storage unit of the internal combustion engine controller. However, if power is not supplied to the storage unit such as when replacing the battery, the injection characteristic will be deleted from the storage unit. Thus, if the injection characteristic is not stored in the storage unit when the engine is started, the learning process of the partial lift injection is performed during the engine operation.
In the internal combustion engine controller, an air-fuel ratio learning process of calculating a learning value of an air-fuel ratio and a purge learning process of calculating a concentration of fuel vapor purged to an intake passage when the fuel vapor is purged from a canister to the intake passage may be performed in addition to the learning process of the partial lift injection. The learning result obtained by each learning process is stored in the storage unit in the same manner as the learning process obtained by the learning process of the partial lift injection. Thus, when power is not supplied to the storage unit, the learning results obtained by the air-fuel ratio learning process and the purge learning process are also deleted from the storage unit. Therefore, if such learning results are not stored in the storage unit when the engine is started, the air-fuel ratio learning process and the purge learning process also need to be performed in addition to the learning process of the partial lift injection.
The exhaust aspect of the internal combustion engine can be stabilized by completing each learning process. Thus, when the learning result of each learning process is deleted from the storage unit, it is desired that each learning process described above be efficiently performed and completed as soon as possible.